Gelling ophthalmic compositions containing xanthan gum

Abstract

Ophthalmic drug delivery vehicles which are administrable as a liquid and which gel upon contact with the eye are disclosed. The vehicles contain xanthan gum and an ophthalmically acceptable anesthetic agent.

We claim:  
     
       1. An ophthalmic composition having a total ionic strength of about 120 mM or less and comprising an ophthalmically acceptable anesthetic drug and xanthan gum, wherein the xanthan gum has an initial bound acetate content of at least about 4% and an initial bound pyruvate content of at least about 2.5%, provided that the composition does not contain locust bean gum. 
     
     
       2. The composition of claim  1  wherein the amount of xanthan gum is from about 0.3 to about 0.8% (w/v). 
     
     
       3. The composition of claim  1  further comprising one or more agents selected from the group consisting of buffering agents; tonicity-adjusting agents; surfactants; solubilizing agents; stabilizing agents; comfort-enhancing agents; emollients; pH-adjusting agents; and lubricants. 
     
     
       4. The composition of claim  1  wherein the xanthan gum forms a gel having an elastic modulus (G′) of approximately 130 Pa when measured in the Lysozyme Gel Strength Test. 
     
     
       5. The composition of claim  1  wherein the composition has a total ionic strength of about 94 mM or less. 
     
     
       6. An unpreserved, unit-dose ophthalmic composition having a total ionic strength of about 120 mM or less and comprising an ophthalmically acceptable anesthetic drug and xanthan gum, wherein the xanthan gum has an initial bound acetate content of at least about 4% and an initial bound pyruvate content of at least about 2.5%, provided that the composition does not contain locust bean gum or a preservative. 
     
     
       7. The composition of claim  6  wherein the anesthetic drug is selected from the group consisting of proparacaine; lidocaine; cocaine; oxybuprocaine; benoxinate; butacaine; mepivacaine; etidocaine; dibucaine; bupivacaine; levobupivacaine; tetracaine; and procaine. 
     
     
       8. The composition of claim  7  wherein the anesthetic drug is selected from the group consisting of levobupivacaine; proparacaine and tetracaine. 
     
     
       9. An unpreserved, unit-dose ophthalmic composition having a total ionic strength of about 120 mM or less, a pH of about 6-8, and comprising 
       a) 0.2-1.5% (w/v) of an ophthalmically acceptable anesthetic drug;  
       b) 0.3-0.8% (w/v) of xanthan gum having an initial bound acetate content of at least about 4% and an initial bound pyruvate content of at least about 2.5%;  
       c) a buffering agent; and  
       d) a tonicity adjusting agent in an amount sufficient to cause the composition to have an osmolality of 250-350 mOsm/Kg.